Assessed solicited general AEs were fatigue, gastrointestinal symptoms \[nausea, vomiting, diarrhea and/or abdominal pain\], fever and headache. An unsolicited AE covers any untoward medical occurrence in a clinical investigation subject temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product and reported in addition to those solicited during the clinical study and any solicited symptom with onset outside the specified period of follow-up for solicited symptoms.Grade 2 symptoms = occurrence of symptoms discomforting enough to interfere with daily activities. Grade 3 symptoms = symptoms that prevented normal activities. This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).

Grade 2 Fever was defined as oral temperature above (\>) 38.5 degrees Celsius (°C) to less than or equal to (≤) 39.5°C. Grade 3 Fever was defined as oral temperature \> 39.5°C. This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).

SAEs assessed include medical occurrences that result in death, are life threatening, require hospitalization or prolongation of hospitalization or result in disability/incapacity. Related SAEs = SAEs assessed by the investigator as related to the vaccination. This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).

RSV-A is one of the two antigenically distinct subgroups of the Respiratory Synctial Virus (RSV). Antibody titers were determined by neutralization assay and presented as geometric mean titers (GMTs), for a seropositivity cut-off value greater than or equal to (≥) 8 ED60 (Estimated Dilution 60). This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).

PCA concentrations were determined by Enzyme-Linked Immunosorbent Assay (ELISA), presented as geometric mean concentrations (GMCs) and expressed in micrograms per milliliter (µg/mL), for a seropositivity cut-off ≥ 9.6 µg/mL. This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).

PCA concentrations were determined by Enzyme-Linked Immunosorbent Assay (ELISA), presented as geometric mean concentrations (GMCs) and expressed in micrograms per milliliter (µg/mL), for a seropositivity cut-off ≥ 9.6 µg/mL. This primary objective focused only on subjects from the investigational GSK3003891A vaccine groups (GSK3003891A vaccine formulation 1 Group, GSK3003891A vaccine formulation 2 Group and GSK3003891A vaccine formulation 3 Group).